The invention concerns a method for filling a two chamber tube made from plastic and having a substantially circular cross section with a separation wall made from plastic extending between two substantially diametrically opposed connection points of the tube wall, and having a length in excess of the diameter of the tube and which, together with the walls of the tube, defines the two chambers, wherein a filling nozzle is inserted into each chamber for introduction of a filling product, with the tube being sealed after the filling nozzles have been removed. The invention also concerns an apparatus for carrying out the method having a filling unit and a downstream sealing unit for sealing the filled tubes.
Two chamber tubes made from plastic have been known in the art for some time and have the advantage of being able to accept two differing materials in one tube without having the materials come into contact with each other as is e.g. necessary with a two-component glue. A two chamber tube is manufactured from an initially flat multi-layered structure, wherein a plastic layer forming the separation wall is disposed between an upper and a lower tube wall layer. The tube is then subsequently erected to an approximately circular shape, wherein the separation wall, which should diametrically extend within the tube, is significantly longer than the diameter of the tube. In consequence of this excess length, the separation wall does not extend in a linear fashion, rather is curved with unpredictable shape.
A filling nozzle must be introduced into each of the two chambers to fill same. It has turned out that the uncontrollable position of the separation wall often interferes with introduction of the filling nozzles or causes both filling nozzles to be inserted into the same chamber so that the filling process has to be interrupted.
In order to prevent improper filling of the two chamber tube one has attempted to monitor the position of the separation wall prior to the filling procedure using video techniques in order to screen tubes having an undesirable wall position. This process is however difficult from a technical point of view and therefore expensive and leads to a very high fraction of rejected tubes which can not be filled.
It is therefore the underlying purpose of the invention to create a method of the above mentioned kind with which two chamber tubes can be filled in a reliable fashion as well as an apparatus with which the method can be carried out in a simple and economical fashion.